Greetings All:

I have been struggling with my 1945 WM 20 for just about a year. I have had trouble getting to run but it has started on occasion. I was away for a couple months and, upon my return, I can not turn the engine over. It will budge a couple degrees but that is it. Here is what I tried thus far: I've tried with the spark plug removed in case the valve lifter was not proper - The kick start works with the clutch engaged - I've tightened the drive cush nut - I've reset the oil pressure ball and spring. I removed and drained the oil pan.
I've reached my wits end (a short journey) and am hoping someone can suggest next steps. I will greatly appreciate any assistance.
Stay Well, Barry

email (option): bcubed77@comcast.net

Hello Barry,I'M sure someone will post with some more detailed suggestions in a while but to eliminate any possibility of it being a problem with the transmission/kickstart/primary chain I would remove the primary casing,take off the primary chain and attempt to turn over the engine by hand (using a spanner or similar)That way you can pin the problem down.If it is the engine that's tight remove the head,look at the bore.Good luck,Mick.

After my mag seized in Normandy it would be a good idea to eliminate the mag/dyno before you start stripping the engine.

email (option): horror@blueyonder.co.uk

Yes, Mag is easy to check, take points cover off, and see if the points block moves a little, there's always backlash in the gears! if totally solid, remove mag.

What about the seizing of oil pumps on M20's??

Cheers,

Lex

email (option): welbike@welbxxx.net

Could it be the little spacer that goes in behind the Cush drive? If it's missing it can lock the engine. Failing that is the centre spacer between the two bearings present?

email (option): davmax@ntlworld.com

The spacer behind the cush drive assembly can get worn and seize into the crankcase... (it isn't hardened when it is a separate piece to the crankshaft sleeve). This can lock the engine...

Unfortunately if that is the problem they are a bugger to get out...

Whilst the M20 oil pump can get tight due to corrosion in the Mazac pump body die castings the engine will continue to drive it, although this will cause wear of the pump drive spindle.....

Personally I wouldn't run an M20 that hasn't had the pump checked for this common fault...It can be rectified...

However, I have never known one in any BSA single completely seize and stop the engine turning...Ian

email (option): ian@wright52.plus.com

I suspect the gearbox. Hasnt that happened before ?
Can you change gears with the lever ?

Hello Aii:
I've tried the mag and gearbox and they seem fine. I'm following on Ian's suggestion and have removed the cush nut assembly and was able to remove one bush. It is about 1/16" wide, .02" thick and beveled at maybe 40 degrees. There is a second one that is flat and about 1/8" wide but I can not remove it. I can rotate it so I do not think that is binding. Any comments Ian?
I've removed the head and nothing obvious there.
The piston is 1 5/8" down from the top of the cylinder. Do I dare put a block on the piston and give it a rap to try to free it?
Any suggestions will be greatly appreciated. Best Regards, Barry in NH

email (option): bcubed77@comcast.net

Something is seriously amiss Barry.(seized or jambed). Don't hit anything with a block of wood. Since you've gone this far, you might as well continue stripping bits off until you come across the problem. It's not much work to remove the timing cover, then the cams and mag idler wheel. If that doesn't prove anything, then drop the oil pump out after removing the four nuts and plate from underneath the crankcase. The oil pump bodies are made from Mazak and have a habit of swelling and becoming tight to turn if left unattended for long periods. If the engine still refuses to turn, then I think it would be time to remove it for a total strip and investigation. Ron

email (option): ronpier@talk21.com

Hi Ron:

Thanks for your input. You have given me much to consider. I will definitely put my hammer away before I do any more damage!
Thanks Again, Barry

email (option): bcubed77@comcast.net

Hello all,

I just want to add more food for thought with Barry's problem. Also, Barry feel free to correct me if I get any details wrong.

Back in mid June Barry made the trip up to my house so that we could both try starting his bike up for the first time. The trip to my house is about 125 miles, and that day it was raining quite heavily. We did manage to get it going briefly so it does indeed run. It sounded good, but then she sputtered out. I believe that it was our own fault as we didn't stay on the throttle as diligently as we should have. We tried to get it going again but the 'ole gal just wore Barry out. I was unable to do my part because I had spinal surgery just three weeks earlier. We then loaded it back onto an open trailer and Barry made the 125 mile rip back home in the rain. We also wrapped the carb up in plastic for the return ride home. After that, the bike sat for the rest of the summer. When Barry returned to work on it again that's when he discovered it was seized up. So I'm relatively certain that it is not a catastrophic mechanical failure......I think, as it was turning freely before the extended period of sitting.

Earlier Horror mentioned a seized mag. Is it possible that the extreme wet conditions that day could create a situation where something in the mag has slightly oxidized/rusted enough to cause the mag to seize? I'm thinking if the mag pinion gear was removed, then Barry could try to kick it over to see if the engine turns over. If it does, then the mag is the problem. If it doesn't, then it's on the engine side of things. Oh by the way, he did remove the primary chain and the gearbox operates freely. Barry, have I summed this up correctly? Thanks for the help!

James

email (option): jamescusteau@yahoo.com

seized oilpump.

Tight maybe...Never seen a seized one in an engine that would stop it running..Ian

email (option): ian@wright52.plus.com

Earlier Horror mentioned a seized mag. Is it possible that the extreme wet conditions that day could create a situation where something in the mag has slightly oxidized/rusted enough to cause the mag to seize? I'm thinking if the mag pinion gear was removed, then Barry could try to kick it over to see if the engine turns over. If it does, then the mag is the problem.

James[/quote]

It would have been one of my first thought too James, Especially when I saw Horror struggle with a same situation in France. But Barry says he's checked the mag. Ron

email (option): ronpier@talk21.com

I had an old locked up motor which i foolishly managed to free up with much force only to find the oilpump seized and stripped driven pinion.